2017/11/30 by Yvan Dossmann, Florence Pollet, Philippe Odier +1 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Cascade #Energy cascade #Forcing (mathematics) #Instability #Intermittency #Internal wave #Marine and coastal ecosystems #Mixing (physics) #Ocean Waves and Remote Sensing #Oceanographic and Atmospheric Processes #Thermal diffusivity #Turbulence #physics.flu-dyn
paper · pdf · doi:10.1002/2017jc013309
published as Journal of Geophysical Research: Oceans 122, 9906-9917 (2017)
openalex publication_date 2017/11/30 · openalex created_date 2018/04/06 · arxiv created 2018/05/11 · arxiv updated 2021/02/10 · openalex updated_date 2026/08/05
Abstract The energy pathways from propagating internal waves to the scales of irreversible mixing in the ocean are not fully described. In the ocean interior, the triadic resonant instability is an intrinsic destabilization process that may enhance the energy cascade away from topographies. The present study focuses on the integrated impact of mixing processes induced by a propagative normal mode‐1 over long‐term experiments in an idealized setup. The internal wave dynamics and the evolution of the density profile are followed using the light attenuation technique. Diagnostics of the turbulent diffusivity K T and background potential energy BPE are provided. Mixing effects result in a partially mixed layer colocated with the region of maximum shear induced by the forcing normal mode. The maximum measured turbulent diffusivity is 250 times larger than the molecular value, showing that diapycnal mixing is largely enhanced by small‐scale turbulent processes. Intermittency and reversible energy transfers are discussed to bridge the gap between the present diagnostic and the larger values measured in Dossmann et al. ( ). The mixing efficiency η is assessed by relating the BPE growth to the linearized KE input. One finds a value of , larger than the mixing efficiency in the case of breaking interfacial wave. After several hours of forcing, the development of staircases in the density profile is observed. This mechanism has been previously observed in experiments with weak homogeneous turbulence and explained by Phillips (1972) argument. The present experiments suggest that internal wave forcing could also induce the formation of density interfaces in the ocean.